1. Field of the Invention
The invention relates to a screw driver handle, more particularly to a high torsion ratcheting driver handle.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional driver handle for a driver bit is shown to include an elongated body 1, a ratcheting mechanism 2, a turnable disc 6, a spring member 9, a selector cap 7 and a shank 8.
As illustrated, the elongated body 1 has an end portion formed with an inner annular wall 111A that extends in an axial direction to define an axial hole 112A which opens at the end portion. The ratcheting mechanism 2 includes an elongate ratcheting housing 201 disposed in the axial hole 112, and has an end wall formed with an axial bore 2a to receive a gear member 3 therein and two lateral pawl receiving holes 2b in communication with the axial bore 2a to receive left and right spring-biased pawl units 4, 5, respectively, therein such that the tooth portions 5a of the latter mesh with the gear member 3. The end wall of the ratcheting housing 201 further has two spring-retaining curved slots 2c formed therethrough. The gear member 3 defines a non-circular hole 3a that extends in the axial direction and that accommodates the shank 8 non-rotatably therein. The turnable disc 6 is disposed for turning around the axial direction in the clockwise and counterclockwise directions, and has a central hole for passage of the shank 8 and an axially extending tongue 6a that projects into the axial bore 2a of the ratcheting housing 201 to abut against the tooth portion of the right pawl unit 5 so as to the prevent engagement between the gear member 3 and the right pawl unit 5. Two end portions 9a of the spring member 9 extend in the axial direction through two insert holes 6c of the turnable disc 6 and engage the curved slots 2c of the ratcheting housing 201 to provide a resilient retarding force during turning of the turnable disc 6. The selector cap 7 has a central hole for passage of the shank 8, and a plurality of angularly spaced plugs 7a inserted into socket holes 6b of the turnable disc 6 so as to transmit turning of the selector cap 7 to the turnable disc 6.
A disadvantage of the conventional ratcheting driver handle resides in that the spring members 4 of the pawl units 5 must be maintained at an appropriate tension force because, in case the tension is considerable strong, the user must exert a considerable force to turn the elongated body 1 in the clockwise direction in order to cause idle rotation of the ratcheting housing 201 relative to the gear member 3. In addition, because only one of the pawl units 5 is engaged to the gear member 3, thereby providing a poor torque on a workpiece when the elongated body 1 is turned about the axial direction in the counterclockwise direction in order to perform a tightening operation.